Push-type mechanical pencil

ABSTRACT

A pushing force applied to an end cap of a push-type mechanical pencil compresses initially a first spring to expose a guide tube at the tip of an inner casing to the outside of a barrel. Then, the stronger pushing force applied successively to the end cap compresses a second spring to eject a lead through the guide tube by means of a lead ejecting means.

United States Patent Horie 1 1 Jan. 30, 1973 [54] PUSH-TYPE MECHANICALPENCIL [56] References Cited 'lnventor: Yukio HOl'iE, TOkyO, Japan [73]Assign Dal Bung Kabushiki Kaisha 261455 7/1882 Hoffman ..401 95x (l/k/aThe Japan (30-, 3,153,479 10/1964 Hultgren .40l/78 -)5 Tokyo, Japan270,567 1/1883 Hoffman ..401 93 x l,355,026 l0/l920 Austin ..40l/l I7[22] 1971 2,649,074 8/1953 Burchett ..401/117 [21] Appl. No.2 104,163

Primar ExaminerLawrence Charles Related US. Application Data AtmmeyyE|i0t S Gerber [62] Division of Ser. No. 825,837, May 19, 1969,abandoned. [57] ABSTRACT [30] Foreign Application Priority Data APUShiPg force .applied to an cap a push-type mechanical pencilcompresses mmally a first spring to July ll, Japan expose a guide tubeat [he of an inner casing to the I outside of a barrel. Then, thestronger pushing force [52] US. Cl. ..401/94 applied successively to theend cap compresses 3 [5l] Int. Cl, ..B43k 21/22 Second Spring to ejec alead through the guide tube [58] Field of Search ..401/57.88, 107-108,

by means of a lead ejecting means.

1 Claim, 5 Drawing Figures PATENIEDJAII 30 I975 FIG.

FIG. 2

FIG. 3

L 4mm INVENTORF YUK O HoR/E PUSH-TYPE MECHANICAL PENCIL This is adivision of a copending patent application Ser. No. 825,837 filed May19, 1969 now abandoned.

This invention relates to a push-type mechanical pencil.

The lead for use in mechanical pencils has recently been improved andthin leads have been developed. Mechanical pencils now are adapted touse leads of 0.3mm to 0.5mm in diameter. Such thin leads are widely usedfor drafting and for conventional writing. In order to protect such afine lead from breaking, mechanical pencils have a guide tube throughwhich the lead protrudes. The guide tube is provided at the tip of aferrule of the mechanical pencil. As finer leads are used, i.e., morenarrow than 0.5mm in diameter, the diameter of their guide tubes islikewise reduced. Consequently a mechanical pencil having such a fineguide tube may be dangerous or may be deformed, for exam ple, byfalling. Once the guide tube is deformed, it cannot guide the lead.

An objective of the present invention is to provide a push-typemechanical pencil in which a fine lead guide tube is exposed from andconcealed into a barrel by simple operations.

Another objective of the present invention is to provide a push-typemechanical pencil in which the fine lead guide tube is exposed outsideof the barrel and a lead is ejected through the guide tube in turn bypushing operations of different strength.

Other objectives and advantages of the present invention will beapparent from the following description when taken in conjunction withthe accompanying drawings, in which:

FlG. l is a side view of a push-type mechanical pencil incorporating anembodiment of the invention, showing a fine lead guide tube as well asferrule exposed outside of a barrel;

FIG. 2 is a side view of the push-type mechanical pencil of FlG. 1,showing the concealed position of the guide tube;

FIG. 3 is a partially sectioned enlarged side view showing the foreportion of the push-type mechanical pencil of FIGS. 1 and 2; and

FIG. 4 is a partially sectioned enlarged side view of the center portionof the push-type mechanical pencil ofFlGS. 1, 2 and 3;

FIG. 5 is a top plan view of a portion of the inner cylindrical tubularmember showing its slot.

An embodiment of the push-type mechanical pencil according to thepresent invention shall be described with the help of Figures.

ln FIG. 1 the mechanical pencil includes a ferrule l, with a fine leadguide tube 2 protruding through tip of the ferrule 1. A fore end portionof an inner casing 5 is fixed upon, or formed integral with, the rearopen end of the ferrule 1. These parts are exposed outside of afrust-conical fore end portion 4 of a barrel 3. The mechanical pencil isof the push-type and its guide tube 2 is in the exposed portion. An endcap 6 protrudes through the rear opening of the barrel 3. in FIG. 2 theguide tube 2, as well as the ferrule 1, is concealed in the barrel 3. Asthe mechanical pencil is in its concealed position, the end cap 6 islonger than its position shown in FIG. 1. The added length of cap 6 isthe same length as the retracted portions (ferrule 1, guide tube 2 andcasing 5).

The innercasin'g 5 is fixed to the rear open end of the ferrule l, inany convenient manner, or may be formed integral therewith. As shown inFIG. 3, the rear inner end portion of the ferrule 1 and the fore innerend portion of the inner casing 5 are connected together by means of afirst spring-receiving bushing member 42, the connections being at 43and 45. A helical coil spring 8, which serves to eject a lead 11 throughthe guide tube 2, is provided between the first spring receiving member42 and a second spring receiving member 18 (see FIG. 4). Springreceiving member 18 is connected to the rear end ofa lead guide member19, the fore portion of which comprises a chuck member'9 and a ring 10.A lead storing housing 7 is fixed at its fore end to the secondspring-receiving member 18 and connected at its rear end (not shown) tothe end cap 6. As shown in FIG. 5, a cylindrical tubular member 15 has aslot 14 which is hooked at its fore end. Member 15 is positioned betweenthe barrel 3 and the inner casing 5 so as not to move relative to thebarrel. A projection 12 is formed integral with the inner casing 5 nearits front end. Projection 12 is fitted in the slot 14so that the innercasing 5 is slidable relative to the barrel 3 and to the cylindricalmember 15 along the lengthwise direction of the mechanical pencil.Another spring 16, which serves to advance and retract the inner casing5 along the slot 14, is provided between the rear end of the cylindricalmember 15 and another projection 17 formed at the rear end of the innercasing 5.

When the spring 16 is weaker in expansion force than the other spring 8(adapted for the push-type mechanical pencil of this embodiment), theinner casing 5 is advanced initially to expose the guide tube 2 as wellas the ferrule l to the outside of the barrel 3 as describedhereinafter. When a pushing force strong enough to compress the spring16, but not strong enough to compress the spring 8, is applied forwardlyto the end cap 6 of the mechanical pencil in the concealed position inFlG. 2, it compresses the spring 16, as the force is transmitted to therear projection 17 by way of the housing 7, second spring-receivingmember 18, spring 8, first spring-receiving member 42 and inner casing5. Therefore, the inner casing 5 slides forwardly relative to the barrel3 and the fine lead guid tube 2 is exposed outside of the barrel 1.Reference numeral 12a in FlGS. 4 and 5 shows the position of the foreprojection before moving. When fore projection 12 is ad vanced along thehooked slot 14, it comes to the fore end of the slot 14 and is turned toenter into its hook portion 13, thereby the guide tube 2 is maintainedin the exposed position as shown in FIG. 1.

Further, when the pushing force strong enough to compress the spring 8is successively applied in the same way, as mentioned above, the lead 11is ejected by way of a bore 20, guide member 19, chuck member 9 and ring10. As far as the leadejecting means comprising the guide member 19,chuck member and the ring 10 is concerned, the push-type mechanicalpencil of the embodiment of the invention utilizes conventionalstructure.

By rotating slightly the end cap 6 so that the projection 12 may bedisengaged from the hook portion 13, the guide tube 2 in the exposedposition can be retracted in the barrel 3 as shown in FIG. 2. When theprojection 12 is disengaged from the hook portion 13,

the inner casing 5 is retracted by means of the spring 16 to conceal theguide tube 2 in the barrel 3 The spring 8 serves to eject the lead 11through the guide tube and spring 16 serves to advance and retract theinner casing. If the spring 16 is stronger in expansion force than thespring 8, the inner casing 5 is advanced after the lead ejectingoperation has been performed.

In the above-mentioned embodiment the cylindrical member having theelongated slot 14 is provided apart from the barrel 3. But they may beformed integral with each other.

The push-type mechanical pencil of the embodiment of the invention is soconstructed that the exposing of the fine lead guide tube 2 and theejecting of the lead 11 through the guide tube 2 can be maderespectively in turn by simply pushing the end cap 6. The retracting ofthe inner casing 5 to conceal the guide tube into the barrel 3 isobtained by slightly rotating the end cap 6.

What is claimed is:

1. A mechanical pencil comprising a barrel opened at both ends, an innerhollow casing disposed inside of said barrel, lead advancing meanshaving a first spring inside of said inner casing, and an end capprojecting through the rear end opening of said barrel, the improvementof said mechanical pencil comprising a fine lead guide tube at the tipof said inner casing which is slidable relative to said barrel, a firstprojection provided at the outer surface near the front end of saidinner casing, a tubular member disposed between said barrel and saidinner casing and having a hooked slot through which said firstprojection is guided and caught at its hooked portion, a secondspringprovided around the rear cylindrical surface of said inner casing butinside of said barrel, said second spring expanding between said tubularmember and a second projection provided at'the rear portion of saidinner casing and urging said inner casing to the rearward direction ofsaid barrel, and means for transmitting a pushing force applied to saidend cap to said second spring, wherein said second spring is weaker inexpansion force than the first spring, whereby the inner casing isadvanced initially outside of the fore end opening of said barrel andthen a lead is ejected through said lead guide tube.

1. A mechanical pencil comprising a barrel opened at both ends, an innerhollow casing disposed inside of said barrel, lead advancing meanshaving a first spring inside of said inner casing, and an end capprojecting through the rear end opening of said barrel, the improvementof said mechanical pencil comprising a fine lead guide tube at the tipof said inner casing which is slidable relative to said barrel, a firstprojection provided at the outer surface near the front end of saidinner casing, a tubular member disposed between said barrel and saidinner casing and having a hooked slot through which said firstprojection is guided and caught at its hooked portion, a second springprovided around the rear cylindrical surface of said inner casing butinside of said barrel, said second spring expanding between said tubularmember and a second projection provided at the rear portion of saidinner casing and urging said inner casing to the rearward direction ofsaid barrel, and means for transmitting a pushing force applied to saidend cap to said second spring, wherein said second spring is weaker inexpansion force than the first spring, whereby the inner casing isadvanced initially outside of the fore end opening of said barrel andthen a lead is ejected through said lead guide tube.